First Year End Review: Digestive System

Digestive System Overview

• GI organs are located within the peritoneal cavity; kidneys are retroperitoneal.
• Greater omentum is a fatty membrane extending from the stomach to intestines.

Oral Cavity

• Teeth consist of enamel (outer layer) and dentin (inner connective tissue).
• Saliva contains amylase, initiating carbohydrate digestion.

Pharynx and Esophagus

• Pharynx is a passageway for both food and air.
• Esophagus is located posterior to the trachea.

Stomach Anatomy

• Located below the diaphragm.
• Parietal cells produce:
  • Hydrochloric acid (HCl) for protein denaturation.
  • Intrinsic factor for Vitamin B12 absorption in the ileum.
• Chief cells secrete pepsinogen, which activates to pepsin for protein digestion (breaking down proteins to amino acids).
• The pyloric sphincter regulates the release of stomach contents into the small intestine (SI).

Small Intestine Structure

• Comprised of three sections: duodenum, jejunum, ileum.
• Lined with villi and microvilli to enhance surface area for optimal digestion and absorption.

Accessory Organs

• Liver:
  • Produces bile for lipid emulsification.
  • Stores glycogen (glucose reserve) and synthesizes plasma proteins such as albumin, clotting factors, angiotensinogen, and complement proteins.
  • Converts ammonia (from protein metabolism) into urea.
• Gallbladder (GB):
  • Stores, concentrates, and releases bile into the duodenum via the common bile duct.
• Pancreas:
  • Produces amylase (for carbohydrates), lipase (for lipids), and trypsin (for proteins).

Large Intestine Functionality

• Primary roles include waste elimination (feces) and water absorption.
• Gut bacteria aid in extracting B vitamins and Vitamin K.
• Fermentation of indigestible carbohydrates (e.g., cellulose) produces gas.
• Sections include: cecum (with appendix), ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anus.

Blood Flow in Digestion

• Oxygenated blood is supplied to the GI tract by superior and inferior mesenteric arteries (branches of the aorta).
• All blood exiting GI organs passes through the hepatic portal vein to reach the liver.

Digestive System Overview

• GI organs are located within the peritoneal cavity; kidneys are retroperitoneal.
• Greater omentum is a fatty membrane extending from the stomach to intestines.

Oral Cavity

• Teeth consist of enamel (outer layer) and dentin (inner connective tissue).
• Saliva contains amylase, initiating carbohydrate digestion.

Pharynx and Esophagus

• Pharynx is a passageway for both food and air.
• Esophagus is located posterior to the trachea.

Stomach Anatomy

• Located below the diaphragm.
• Parietal cells produce:
  • Hydrochloric acid (HCl) for protein denaturation.
  • Intrinsic factor for Vitamin B12 absorption in the ileum.
• Chief cells secrete pepsinogen, which activates to pepsin for protein digestion (breaking down proteins to amino acids).
• The pyloric sphincter regulates the release of stomach contents into the small intestine (SI).

Small Intestine Structure

• Comprised of three sections: duodenum, jejunum, ileum.
• Lined with villi and microvilli to enhance surface area for optimal digestion and absorption.

Accessory Organs

• Liver:
  • Produces bile for lipid emulsification.
  • Stores glycogen (glucose reserve) and synthesizes plasma proteins such as albumin, clotting factors, angiotensinogen, and complement proteins.
  • Converts ammonia (from protein metabolism) into urea.
• Gallbladder (GB):
  • Stores, concentrates, and releases bile into the duodenum via the common bile duct.
• Pancreas:
  • Produces amylase (for carbohydrates), lipase (for lipids), and trypsin (for proteins).

Large Intestine Functionality

• Primary roles include waste elimination (feces) and water absorption.
• Gut bacteria aid in extracting B vitamins and Vitamin K.
• Fermentation of indigestible carbohydrates (e.g., cellulose) produces gas.
• Sections include: cecum (with appendix), ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anus.

Blood Flow in Digestion

• Oxygenated blood is supplied to the GI tract by superior and inferior mesenteric arteries (branches of the aorta).
• All blood exiting GI organs passes through the hepatic portal vein to reach the liver.

Test your understanding of the digestive system with this comprehensive quiz. Covering the anatomy of the peritoneal cavity, organs, and enzymes involved in digestion, this quiz is designed for first-year students. Review key concepts and functions related to the gastrointestinal tract and its components.